Always come down the mountain in the same gear you go up, I put the trans into 4th gear on anything 6- percent grade or less on a stepper grade I slow down & use 3rd. Try to keep the climb at 1700-2100 rpm & the downhill 1700 or less.
Keep your engine brake engaged on the downhill, turn it off on the climb.
Im sure your going to hear other suggestions, this is just what I do & I drove a semi for 35 years before retiring.
2014 Essex, 2015 Ram 1500, 2008 Harley Road King